Sunday, November 1, 2009

Logging and nice graphs

Hi all,

This week I worked on improving the system we use for logging. Well, it was not really a "system" but rather a pile of hacks to measure in custom ways timings and counts and display them. So now, we have a system :-)

The system in question was integrated in the code for the GC and the JIT, which are two independent components as far as the source is concerned. However, we can now display a unified view. Here is for example pypy-c-jit running pystone for (only) 5000 iterations:

The top long bar represents time. The bottom shows two summaries of the total time taken by the various components, and also plays the role of a legend to understand the colors at the top. Shades of red are the GC, shades of green are the JIT.

Here is another picture, this time on pypy-c-jit running 10 iterations of richards:

We have to look more closely at various examples, but a few things immediately show up. One thing is that the GC is put under large pressure by the jit-tracing, jit-optimize and (to a lesser extent) the jit-backend components. So large in fact that the GC takes at least 60-70% of the time there. We will have to do something about it at some point. The other thing is that on richards (and it's likely generally the case), the jit-blackhole component takes a lot of time. "Blackholing" is the operation of recovering from a guard failure in the generated assembler, and falling back to the interpreter. So this is also something we will need to improve.

This week I worked on improving the system we use for logging. Well, it was not really a "system" but rather a pile of hacks to measure in custom ways timings and counts and display them. So now, we have a system :-)

The system in question was integrated in the code for the GC and the JIT, which are two independent components as far as the source is concerned. However, we can now display a unified view. Here is for example pypy-c-jit running pystone for (only) 5000 iterations:

The top long bar represents time. The bottom shows two summaries of the total time taken by the various components, and also plays the role of a legend to understand the colors at the top. Shades of red are the GC, shades of green are the JIT.

Here is another picture, this time on pypy-c-jit running 10 iterations of richards:

We have to look more closely at various examples, but a few things immediately show up. One thing is that the GC is put under large pressure by the jit-tracing, jit-optimize and (to a lesser extent) the jit-backend components. So large in fact that the GC takes at least 60-70% of the time there. We will have to do something about it at some point. The other thing is that on richards (and it's likely generally the case), the jit-blackhole component takes a lot of time. "Blackholing" is the operation of recovering from a guard failure in the generated assembler, and falling back to the interpreter. So this is also something we will need to improve.